APPLICANT'S ABSTRACT: Alcoholics have an increased incidence of pulmonary diseases that are in part due to altered lung host defense functions related to alcohol toxicity and a strong tendency for alcoholics to smoke heavily. A major airway defense function that is impaired during both alcohol ingestion and cigarette smoking is the mucociliary clearance system. One possible mechanism of mucociliary impairment common to both alcohol ingestion and smoking is acetaldehyde exposure since acetaldehyde is produced during the metabolism of ethanol both by the liver and locally in the airways and is also found in significant amounts in the vapor phase of cigarette smoke. This is important because acetaldehyde is a highly reactive molecule that has been recognized as a significant toxin in biologic systems related to its ability to covalently bind to reactive protein residues. Preliminary experiments have demonstrated the influence of acetaldehyde on bronchial epithelial cell cilia. These studies established that acetaldehyde is directly toxic to ciliated airway epithelial cells causing cilia slowing or paralysis, inhibits cilia dynein ATPase activity, and binds to cilia proteins critical for motility especially dynein and tubulin. It is hypothesized, therefore, that: Acetaldehyde impairs airway cilia function by binding to critical cilia proteins, including dynein and tubulin, in concentrations encountered during alcohol ingestion and cigarette smoking. To test this hypothesis the following specific aims are proposed: 1) Assess the ability of acetaldehyde to bind to axonemal dynein and tubulin and impair the ATPase activity of dynein. These experiments will measure stoichiometric and competitive acetaldehyde binding to and functional impairment of purified cilia dynein and tubulin. 2) Elucidate the mechanism(s) by which acetaldehyde binding impairs the interaction of axonemal dynein with tubulin and microtubules. These experiments will examine acetaldehyde's effect on dynein's ability to enhance microtubule polymerization and translocate microtubules in a cell-free system. 3) Assess the importance of acetaldehyde exposure as a cause of cilia dysfunction in the setting of alcohol and smoke exposure. These experiments will quantify acetaldehyde-protein binding and dysfunction in the cilia of tissues exposed to acetaldehyde vapor, cigarette smoke and ethanol both in vitro and in vivo.